General Description : A semi-crystalline, white engineering thermoplastic very similar to nylon 6,6 with which it is in many respects interchangeable. Its melt viscosity is not quite as low as 6,6 so it is generally slightly easier to process and often preferred for moulding. Relative to 6,6 it has somewhat higher impact strength but somewhat lower strength and stiffness and higher water absorption (the highest of all nylons).

It can be monomer cast, commonly called just cast - ie.polymerised in a mould direct to a semi-fabricated shape. This allows the production of thick sections without voiding and gives a product with a slightly different balance of properties - a little stronger and stiffer, slightly reduced extensibility and impact strength.